As a composite matrix resin having high fluidity, high wettability and high filling capability, cyclic butylene terephthalate (CBT) oligomer is a cyclic oligomer composed of dimers to heptamers. Due to its low melt viscosity (24 mPa·s, 190° C.), the CBT may quickly wet various reinforcers after melted. By adding a catalyst, poly(butylene terephthalate) (PBT, where the poly(butylene terephthalate obtained by polymerizing CBT is marked as pCBT for distinguishing from the conventional PBT) having a high molecular weight may be obtained by ring-opening polymerization at a temperature lower than the melting point of the resulting product. The reaction is easily controllable, has no release of small-molecular by-products and no generation of reaction heat, and may provide for quick shaping. As the only industrialized aryl cyclic oligoester at present, the CBT is highly representative and has attracted the common attention from both industry and academia. However, the CBT is usually crystallized while being polymerized during a polymerization reaction and there are no knots between molecules, so the pCBT is highly brittle and insufficient in comprehensive mechanical properties.
Due to its large specific surface, low cost, no toxicity, good environmental compatibility and high temperature resistance and other excellent characterstics, nanosilicon dioxide (SiO2) is regarded as excellent reinforcing material. Given that nanosilicon dioxide is high in surface energy and very easy to be agglomerated, it is difficult by a common blending method to achieve the uniform dispersion in nano-scale and the excellent interface adhesion between nanosilicon dioxide particles and polymer matrix material, therefore, during preparing a silicon dioxide nanocomposite, it is required to perform surface modification to improve the interface compatibility of nanosilicon dioxide particles with the matrix and the dispersibility of nanosilicon dioxide particles in the matrix. This is the key to realize the reinforcing and toughening of matrix material by nanosilicon dioxide particles.